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Double sinks are generally a lot larger than traditional sinks and give you a much larger workspace. Having two sinks can be a big advantage, and you’ll more people are now deciding that thebest kitchen sink stylefor them is a double basin vanity.
DIY plumbing is often a step too far for some people, but it’s a great way to save some money and get the satisfaction of installing something yourself. The size of a double sink vanity can make it even more intimidating, but it can certainly be done without professional help.
This guide will explain everything you need to know about the pipes, connections, fittings and provide astep-by-stepguide on how to plumb a vanity sink.
Page Contents (Click Icon To Open/Close)
How Do You Rough-In PlumbingForA Sink?
Arough-inis the step of the process where you’ve made all your holes in the wood, walls, floorboards etc., but you haven't yet connected up to your pipes. You should have measured everything, and this is your opportunity to make sure everything fits before securing it.
For a sink, there's a couple of key measurements:
- Vertical Supply Lines
There will be two holes for these usually. These should be 2-3 inches above the drain pipe for each sink. - Horizontal Supply Lines
These should be located 4 inches on either side of your drain pipe. - Side To Side Buffer
You should leave at least 15 inches around the side of the sink. - Front Buffer
Nothing should be installed less than 21 inches in front of the sink. - Sink Drain Height
Your kitchen sink should be at least 28 inches from the floor. For bathroom sinks, this is typically 24 inches. - Vertical Discharge
This should be 16-20 inches from the floor.
For double sinks sharing the same drain, you should make sure there is at least 30 inches between them. Where you have sinks of different heights, make sure that there’s no more than 6 inches difference.
It’s imperative to measure and mark these points accurately during the rough-in, or you could face some serious issues with your plumbing. A full guide to doing this accurately is in the video below.
How To Plumb Your Double Kitchen Sink
Plumbing a kitchen sinkcan be intimidating, especially if you have a double basin. First, you need to get all your plumbingtoolstogether, and then follow these steps:
Plumbing A Double Kitchen Sink & Drain
1
Turn Off Your Water Supply
This can be done by using your primary shut-off valve to stop the water supply to the whole house or by using your fixture shut-off valve to stop the water supply to the particular fitting. We’d recommend the fixture shut-off valve if you have one.2
Measure Up
Measure the distance between the shut-off valves and the faucets. This will determine how long your supply pipes need to be.3
Connect The Water Supply
Install flexible piping to your faucets with a hot pipe and a cold pipe. The hot pipe should go to the left faucet and the cold to the right.4
Install The Tail Pieces
Measure and cut two tail pieces. One should be installed underneath each sink and should be 2-3 inches long. Often with double basins, one will be deeper than the other; you should make sure the tailpieces extend to the same length, so you may need to trim one accordingly.5
Fit The J Pipes
J- pipes will connect the tailpieces into the tee connectors, ultimately connecting the plumbing between the two sinks. Measure them accordingly and then fit a washer and nut to each tailpiece before sliding the J-pipe onto the end. You can then tighten the nut to secure it.6
Attach The Tee Connector(Video) Double Bowl Sink with Garbage Disposal Drainage Installation - Keeney Manufacturing
Fit the Tee connector to the two J-pipes and attach using a washer and nuts.7
Connect The P-trap
Slip a washer and nut over the end and connect the P-trap. This will be used to help stop any bad odor coming back up your pipes.8
Test The System
Tighten all the nuts with a wrench and make sure they’re secure. Test the whole system by running water through the system and looking for leaks. The image below shows what it should look like.
Plumbing A Double Kitchen Sink With Garbage Disposal
Garbage disposalsare a great way to break down food waste so it doesn’t clog up your plumbing. The garbage disposal will usually sit under just one sink, and all food waste should be directed into that one. To install a garbage disposal in a double sink, you need to:
1
Disconnect All Electricals
Make sure the garbage disposal is completely disconnected with no electricity running through it.2
Remove The Extension Pipe
Remove the section of pipe between the sink and the P-trap. This is where your garbage extension will sit.3
Install The Garbage Disposal
Attach the garbage disposal to the flange in the sink using plumbers putty around the edge. Use a mounting ring on the underside of the flange and snap it back to secure it in place. Use a screwdriver to secure the fitting.4
Attach To The Drain
Attach the pipes to the bottom of the garbage disposal so that water can flow through it into the P-trap.5
Test The Connection
The garbage disposal should now fit, so both sinks are flowing through it. Test the connection and make sure this is the case and that all food waste will be caught in the disposal.
advantages of Double Kitchen Sinks
Double kitchen sinks aren’t a very new revelation, but they're becoming increasingly popular. There are a few key features that really set them apart from your traditional kitchen sink:
- Keeps The Clean Dishes Aside
We all know that surface space is at a premium in your kitchen. By having two sinks, you can keep your clean dishes in one to dry, removing the need for space-consuming drying racks where you’re trying to work. - One Sink Is Specifically For Garbage Disposal
Garbage disposals are a great wayto remove food waste from your kitchen safely. They literally churn up the bits of food until they’re small enough to pass through your plumbing withoutclogging it. A garbage disposal is often installed under one sink so that you can scrape food into it. This keeps your other sink free to be used as needed. - Separate Soaking And Cleaning
If you have some tough stains on a pan, you need to let it soak, but having your sink completely occupied is frustrating and limits what you can do. Having two kitchen sinks allows you to continue using one sink while your pots and pans soak in the other, making your whole kitchen more efficient. - More Multi-Tasking And Getting Things Done
Having two sinks just generally makes you more efficient. You can do more than one job, and you can have more than one person working at the sink. This ultimately makes life easier at home.
Disadvantages of Double Kitchen Sinks
As with any home purchase, you need to considerboth sides of the equation. Double kitchen sinks aren’t for everyone, and there are a few things you need to consider:
Consumes Large Counter Space
Double kitchen sinks aren’t designed for compact kitchens. Double kitchen sinks can be over 48 inches long, which can really eat into your workspace. If you’re in an active kitchen, you may just decide that the workspace is more important.
Eats Up Under-Counter Storage Space
Similarly, double kitchen sinks can take up a lot of your storage space. Sink cabinets have no drawers or shelves and are generally just used for cleaning products. Having two of these means you’ve lost some valuable kitchen real estate.
Less Space For Washing Large Items
Some double kitchen sinks are actually more narrow or shallow than sink basins. This can make it more challenging to wash larger items like roasting dishes or baking trays.
More Expensive
You can find great value double and kitchen sinks, but on the whole, you'll pay more for a double sink. You should consider your budget before you commit to one or the other.
People also Ask (FAQs)
Does a double sink need two traps?
No, it’s not a requirement to have twoP-trapson a double sink because they will flow through the same drains. However, there is no issue in having two P-traps if they drain independently from each other.
Can you connect two sinks to one drain?
Yes, plumbing under the sink will connect two sinks, so they drain together.
Can two sinks share a vent?
Yes, but only where both sinks are the same level. If one sink is lower than the other, then the vent might not be at the right height to be effective.
Can I swap a single-bowl for a double-bowl sink?
Yes, providing you have enough space and the countertop materials are appropriate. You may need to make some minor adjustments to your kitchen, and you will need to plumb the double sink correctly.
Compare single Vs double sinks here.
How much does it cost to install a double kitchen sink?
The cost of your kitchen sink will vary massively depending on the make and model you go for. A good double kitchen sink can cost anywhere from $500-1500, and if you hire a professional, it will likely be another $300-500 on top of that. That money will obviously be saved if you install it yourself.
Conclusion
Installing a doublekitchen sinkis a great way to make your kitchen more efficient. It can transform your kitchen into a more efficient workspace and allow you to carry out multiple jobs at once in the space. Plumbing a double sink vanity isn’t as difficult as it seems. It's all about taking it one step at a time.
Hopefully, this article has given you everything you need to get started and install the double vanity sink you've always wanted in your home.
Ian Haynes
Ian Haynes is an expert writer who has successfully deployed over 500 plumbing pages and other related content. He has an excellent understanding of home plumbing issues and translates his experiences via Plumbing Lab so readers can have a better understanding of common household problems. Outside of his work, Ian likes exploring Brooklyn with his Labrador.
Ian Haynes is an expert writer who has successfully deployed over 500 plumbing pages and other related content. He has an excellent understanding of home plumbing issues and translates his experiences via Plumbing Lab so readers can have a better understanding of common household problems. Outside of his work, Ian likes exploring Brooklyn with his Labrador.
FAQs
How do you plumb a double bowl kitchen sink with disposal? ›
And feed the nut up the pipe. Screw the tailpiece nut onto the strainer to attach the tailpiece.
Where do you put a garbage disposal in a double sink? ›The idea is that you use the large sink for cleaning dishes or soaking and then the other sink is available for prep usage, peeling etc. So, the disposal would go on the small bowl.
How should a double sink drain be plumbed? ›Connect the tee to the waist arm by hand tightening the slip joint nut and washer connect the second
How should a garbage disposal be plumbed? ›Disposal system anatomy
If you have a double sink, the best way to plumb a disposal is to run its discharge tube directly to a tee below the opposite sink. The tube must drop about 1/4 in. in order to drain properly.
While both sinks have a separate drain, they do connect. One tends to drain into the garbage disposal while the other has a separate drain. However, they intersect at the main drainage line. If you find your sink filling with water on both sides, that's likely due to a clog in the main drainage line or P-trap.
Can 2 sinks share the same water line? ›In most cases, you can easily adapt the supply and drain pipes to accommodate two sinks, using tee fittings, special valves, extension pipes and hoses. You may have to vent each sink separately, though, depending on your local plumbing codes.
Does a double sink need two traps? ›A double bathroom sink installation rarely requires more than one P-trap. The usual practice is to connect the two sinks to a tee and then feed the tee into a single P-trap, which then connects to the drain. The pipes you use to connect the sink to the P-trap are the same type the P-trap is made from.
Does a double sink need two drains? ›A double sink vanity has two sinks. Each sink will need its own drain. But two sinks don't need their own p-traps. It is common practice for them to share one trap.
Why does my garbage disposal water comes up in the other sink? ›One of the most common causes of garbage disposal backing up into another sink is a clog in the drain line. If this is the issue, then it is a fairly easy fix – you may be able to use a standard plunger to clear the drain. Begin by filling up the other sink (not the one with the disposal) with water.
How does a double sink connect? ›The drains for a double kitchen sink typically connect to a single P-trap, which then connects to the drain. You can install a double sink drain in more than one way, but the most common method is to extend a horizontal drain arm with a 90-degree elbow from each sink to a tee fitting that connects to the trap.
How far can you run a 2 sink drain? ›
When builders look only at the table without reading the text, they find that a 2-inch-diameter drain can run a maximum distance of 8 feet to the vent.
Why does one side of double sink not drain? ›When your double kitchen sink clogs on one or both sides, you likely either have a clog in your garbage disposal and/or a blockage within your main drainage water line.
Does drain pipe need to be lower than garbage disposal? ›The drain into the wall needs to be below that of the disposal and sink, there's no way to beat gravity with this.
How far below the garbage disposal should the P-trap be? ›Maximum Distance
However, the Universal Plumbing Code stipulates that the total developed length of all tailpieces, arms and fittings connecting the drain to the p-trap must be 24 inches or less.
Do I Need An Air Gap If I Have A Garbage Disposal? Garbage disposals require an air gap to prevent cross-connections and contamination that may occur via waste or discharged water.
Does the garbage disposal need to be next to the dishwasher? ›Although dishwashers usually connect to a garbage disposal, providing there's one present, it isn't necessary. You can easily bypass the appliance with specific piping attachments. If you don't have a garbage disposal with your dishwasher, you must include an air gap within the new dishwasher installation.
Is the dishwasher supposed to be connected to the garbage disposal? ›It is recommended to connect the dishwasher discharge drain into the disposal for this very reason. Food will eventually get trapped in the dishwasher drain when it does you experienced this problem of your dishwasher not working properly.
Is the dishwasher hooked up to the garbage disposal? ›A dishwasher does not have a separate drain as part of your home's plumbing system. Instead, it drains through the disposal. That includes any food debris washed off the plates and bowls during the cleaning cycle. When the disposal is draining slowly or is clogged, those problems can affect the dishwasher.
Do you have to vent a double sink? ›All kitchen sinks need vents. Without them, air is not able to get into the pipes which creates negative pressure within the system. This can form a suction on the drain trap, allowing sewer gas to leak into your home.
Is it worth having two sinks in kitchen? ›Whatever you decide for your second sink, it's guaranteed to make cooking easier! Big groups and families sure know how to clean plates at the table, but they can leave a disaster in the kitchen. Having two sinks doubles your clean-up power and allows for a lot more helping hands to join in the fun.
Can two drains share a vent? ›
Common vent
This very simple concept allows two traps to be vented by the same vent. The two traps and their fixture drains can be either at the same level or at different levels, provided that they are on the same floor.
The “S” trap is prohibited under the Uniform Plumbing Code throughout the United States. This is because the “S” trap will siphon or suck water out from the trap which will end up releasing methane (sewer) gases into the home. So, it is a code violation and if you are doing remodeling, you will have to replace it.
Do double sinks increase home value? ›Double vanities also add value to your home. While one sink is typical and essential, two sinks make your home more desirable and attractive to potential buyers. Often, the choice to buy one home over another is how practical the bathroom is; a double vanity definitely adds to that.
Why do Americans want double sinks? ›The most common reason to choose a double sink is that you need more space because you share the bathroom with another person. "Couples these days usually prefer the idea of two sinks for one simple reason," architect Thayer Hopkins told Houzz. "They lead busy lives and need access to the bathroom at the same time."
Is it better to have a double sink or single? ›Single bowl sinks are ideal for small kitchen with limited countertop space; while double sink bowl is perfect if there is a lot of cooking and washing up activity happening and if the countertop space allows for a double sink.
What is it called when you have two sinks in one bathroom? ›What is a double sink vanity? A double sink bathroom vanity has two sinks installed into the cabinet. The countertop is usually cut to accommodate the two sinks as well as the faucets that are installed. Since having two sinks, you're also going to need 2 faucets.
Where does garbage disposal water go? ›Once the scraps have been ground up by the garbage disposal, the water in your pipes carries them to your local wastewater treatment plant. Any solid food pieces that reach the treatment plant are filtered and sent to either an incinerator, anaerobic digestion facility, or landfill.
Can you use Drano in kitchen sink with garbage disposal? ›Drano® Max Gel Clog Remover , Drano® Dual-Force® Foamer Clog Remover, Drano® Max Build-Up Remover, and Drano® Liquid Drain Cleaner may be safely used to unclog a kitchen sink. Short answer: Yes, you can put Drano in a garbage disposal, but read the instructions carefully.
Where does the water drain from a garbage disposal? ›How Does a Garbage Disposal Work? — Appliance Repair Tips
Is it hard to install a double sink? ›It's entirely possible to replace a single sink with a double sink, although it requires a bit of work and money.
What do I need to install double kitchen sink? ›
- Compression nuts.
- Washers.
- New double sink.
- Plumber's putty.
- Sanitary tee.
- PVC pipe.
- Teflon tape/Silicone sealant.
- Kitchen drain trap kit.
Kitchen Remodel - How to Install a Garbage Disposal on a Single Sink
How many fixtures can be on a 2 inch drain? ›| DIAMETER OF PIPE (inches) | MAXIMUM NUMBER OF DRAINAGE FIXTURE UNITS (dfu) | |
|---|---|---|
| Total for horizontal branch | Total for stack greater than three branch intervals | |
| 11/2 | 3 | 8 |
| 2 | 6 | 24 |
| 21/2 | 12 | 42 |
Do Plumbing Vent Pipes Need to be Straight? Plumbing vents need to be straight on the vertical. This is necessary to avoid any vapor locks from occurring. When there is a bend in the vent pipe, moisture accumulates and is trapped.
How many elbows can a plumbing vent have? ›A plumbing vent can have how many bends? 90 Considering this, the number of bends a vent pipe can have is 90. If you want to install 90-degree bends in vent pipes, you can do so.
Why is my double kitchen sink backing up to the other side? ›If both sides of your double kitchen sinks appear clogged and begin to back up, the likely reason is a blockage in your sink's main drain or you have a clogged garbage disposal. Baking soda and hot water can help unclog your drain and works great as a cleaning agent and odor absorbent.
What is the point of two sided sink? ›The primary purpose of double-bowl sinks was to make dishwashing easier: one bowl for soapy water, the other bowl with clean water for rinsing. Nowadays, the double-bowl sink is rarely used for dishwashing. However, this type of kitchen sink does more than make dishwashing easier.
Do you need two water lines for a double sink? ›Each sink will need its own drain. But two sinks don't need their own p-traps. It is common practice for them to share one trap. Of course, you can have two if, for some reason, that works best for your application, but you'll just be spending money you don't necessarily need to spend.
Do you need 2 traps for a double sink? ›A double bathroom sink installation rarely requires more than one P-trap. The usual practice is to connect the two sinks to a tee and then feed the tee into a single P-trap, which then connects to the drain. The pipes you use to connect the sink to the P-trap are the same type the P-trap is made from.
Can two sinks share the same P-trap? ›Two sinks can share a trap as long as the centerline of the outlet (tailpiece) of both sinks is not more than 30-inches horizontally from the trap centerline, per International Plumbing Code (IRC P3201.
Do you need a double sink for a garbage disposal? ›
A garbage disposal can be installed in either a single kitchen sink or on one half of a double sink with a strainer basket in the drain of the second half of the sink. Installing a disposal on a single sink is a much simpler task, as you won't have to contend with the tie-in for the second sink.
Why do I have two drain pipes under kitchen sink? ›When your double kitchen sink clogs on one or both sides, you likely either have a clog in your garbage disposal and/or a blockage within your main drainage water line.
Why do Americans need double sinks? ›The most common reason to choose a double sink is that you need more space because you share the bathroom with another person. "Couples these days usually prefer the idea of two sinks for one simple reason," architect Thayer Hopkins told Houzz. "They lead busy lives and need access to the bathroom at the same time."
How does dual plumbing system work? ›Dual plumbing systems (also known as dual piping) do this by separating water into two types; potable and reclaimed. Potable water can be used for drinking and washing, while reclaimed water is used for irrigation and toilet flushing.
Why are S traps no longer allowed? ›The “S” trap is prohibited under the Uniform Plumbing Code throughout the United States. This is because the “S” trap will siphon or suck water out from the trap which will end up releasing methane (sewer) gases into the home. So, it is a code violation and if you are doing remodeling, you will have to replace it.
What is the benefit of double sink in kitchen? ›The double-bowl kitchen sink isn't just for washing and rinsing dishes. It allows you to accomplish many everyday kitchen jobs with ease and efficiency. Let potatoes soak on one side, while filling up a pot on the other. On a busy weekday evening, defrost a ready-made meal and clean the breakfast dishes simultaneously.
What is a double trap plumbing? ›Monday, March 30, 2020. A double trap is two plumbing traps in tandem, one after the other in line, and this often causes the first trap to get sucked out by the last trap. An example of one sink trap connected to another sink's trap is shown above.
What happens if P-trap is backwards? ›The outlet end of the trap pipe should be lower than the inlet when installed properly. The example shown has it backward, which creates a trap seal more than 4” and makes the drain more likely to clog—and that's a long explanation for why a backwards trap is a bad thing.
Why P-trap is better than S-trap? ›P-traps are generally considered by most to be more effective and consistent in maintaining water trap compared to S-traps. Their design makes them less vulnerable to drying out and losing seal: a properly installed P-trap will never lose its water seal.
How far can sink be from P-trap? ›According to the International Residential Code, the maximum vertical distance between the sink drain and the entrance to the p-trap is 24 inches.
Does drain pipe need to be lower than garbage disposal? ›
The drain into the wall needs to be below that of the disposal and sink, there's no way to beat gravity with this.
Can you put a garbage disposal in a sink that doesn't have one? ›While a garbage disposal can fit any sink, it's essential to be sure that a disposal fits other elements of your home. Before shopping, you should be positive that your space, pipes, and septic system can handle regular contact with extra food waste.